Hints, tips,life hacks to finding trusses/rafters through composite shingle roof?

[Duxa]

Going to be performing a DIY install soon, getting ready, having some ideas about locating trusses without making a billion holes in the roof or tapping just the edge and having the bolt come through the side of the truss/rafter. Id love to hear tips/tricks and life hacks as to how you feel is the best way to locate the trusses. Preferably without expensive equipment and without making holes

I do have attic access to where the panels are going to go (2x6 2ft on center) but I have to put up 3 conduit (EMT) supports in area where I do not have access to the attic (there is no attic). How to be sure I get it in the perfect center spot?

EDIT: Im using Ironridge racking

[Ampster]

The following works if you are using ez flash system because the sheet metal flashing is 12" and should cover any mistakes. If you have exposed rafter tails you can approximate the location. Then tapping or using a high quality stud locator drill a hole. That should get you close within a couple of inches. I fill any mistake with caulking to prevent air leaks but the sheet metal should shed water. Be sure the sheet metal goes fully under a course of shingles especially where the gaps are between the shingles. Sometime I notch the sheet metal to get it further up past the nails. Gravity is your friend because water wants to run downhill. I always have some bituthane to slide under the shingles if in doubt. If you do remove any nails be sure to replace them if possible or put a dab of wet patch sealant under it to keep the shingle from peeling off in wind.

[solarix]

Conduit supports do not need to be fastened down into the rafters. Just use a good adhesive (Chemlink M1) to glue them to the roof.

[littleharbor]

Rafter/truss layout should be fairly accurate, within 3/4". Do your best to find any anomalies in the layout and note them. Once you get the first rafter located you should be able to get close enough to verify by test drilling and having the flashing fully cover the test holes. Use a quality urethane sealant in the test holes

[peatmoss]

I just finished up my install, like Ampster said the the flashing allows for some mistakes. I used a smaller drill bit to drill test holes. I found a rubber mallet worked best to find the rafters.

[Iansworkshop]

Maybe a stud finder would work https://www.amazon.co.uk/Stud-Finder...22179165&psc=1

[Duxa]

Maybe a stud finder would work https://www.amazon.co.uk/Stud-Finder...22179165&psc=1

I do have an electronic stud finder, but I dont know if is good enough to detect it through the layers of shingles.

[Iansworkshop]

I do have an electronic stud finder, but I dont know if is good enough to detect it through the layers of shingles.

I had a go with mine on my workshop tiled roof which has tile battens and it worked provided the stud finder was run horizontally along the roof mid point between the battens, however not such a positive result as through 9mm plasterboard I assume due the depth of the tiles. I guess as u have one try its worth a try

[Ampster]

Circling back, in case your stud sensor can't locate a rafter you can always drill a small pilot hole from the attic. Use that as a reference from the roof to lay out the other rafter locations. As mentioned earlier, caulk the hole and cover it with the mounting flashing.

[scrambler]

I do have an electronic stud finder, but I dont know if is good enough to detect it through the layers of shingles.

The only one that would be up to the job is expensive
https://www.amazon.com/Bosch-D-Tect-.../dp/B005EM93R0

[bob-n]

This video explains a few methods for finding rafters:
https://www.youtube.com/watch?v=OIMEMffezwI

There is a commercial device called RafterEye which uses two magnets in the attic and a compass on the roof. Here's their promotional video, but like the other gizmo mentioned,this device is also expensive.
https://www.youtube.com/watch?v=nqqvubsFKMM
You can build something yourself with two very strong rare-earth magnets and some blocks of wood. Experiment with the magnet orientation on the ground before using it on the roof. I've used a home-made version of RafterEye and it got me close, but wasn't perfect. I don't know if the commercial one is any better. Note that it requires access to the attic to work. Not everyone has that luxury. Another weakness of this idea is that most good compasses use a floating needle that only floats freely when the compass is horizontal. Put it on a sloped roof, and it binds. I'll bet a cell phone app would be better, but haven't tried that.

When it came to my roof, I tried the homemade magnet/compass mentioned above and also the rubber mallet. These got me close enough. Once I had a hole that was close, I could feel through the hole to see which way to go next, and drill one more hole to the side of the miss and hit perfectly.

Here's the procedure that I used: First, I located the first and last rafter, top and bottom (four points) by trial-and-error (mallet, gizmo, whatever). Then I simply measured and drew chalklines to find the others. Once we found the four corners, the rest were correct just from measurements. It is simple to cover any bad holes with sealant and flashing. I used Flashfoot2 from Ironridge which has a large piece of flashing as part of the mount, but other mounts are probably also good. You can find a few more good videos on youtube showing how to install Flashfoot2.